The present invention generally relates to audio signal processing, and more particularly to a video-assisted audio signal processing system and method.
Videocommunicating arrangements generally include a camera for generating video signals, a microphone, sometimes integrated with the camera, a speaker for reproducing sound from a received audio signal, a video display for displaying a scene from a remote location, one or more processors for encoding and decoding video and audio, and a communication interface. In some instances the arrangement includes a speaker and microphone that are separate and not part of an integrated unit.
One problem that arises in videocommunicating applications, and with speakerphones as well, is the feedback of an audio signal from the speaker into the microphone. With this feedback of an audio signal, a participant hears an echo of his/her voice. Various methods are used to eliminate the echo in such arrangements. One approach to dealing with echo is operating in a half-duplex mode. In half-duplex mode, the arrangement is either transmitting or receiving an audio signal at any given time, but not both transmitting and receiving. Thus, only one person at a time is able to speak and be heard at both ends of the conversation. This may be undesirable because comments and/or utterances by a party may be lost, thereby causing confusion and wasting time.
Another approach for addressing the echo problem is an echo-cancellation circuit coupled to the microphone and speaker. With echo-cancellation, a received audio signal is modeled and thereafter subtracted from the audio generated by the microphone to cancel the echo. However, a problem with echo-cancellation is determining the proper time at which to model the received audio signal.
Therefore, it would be desirable to have a system that addresses the problems described above as well as other problems associated with videocommunicating.
The present invention is directed to a system and method for processing an audio signal in response to detected movement of an object in a video signal.
In one embodiment, a circuit arrangement is provided for controlling audio signal transmissions for a communications system that includes a microphone and a video camera. The arrangement comprises a video processor configured and arranged to receive a video signal from the video camera, detect movement of an object in the video signal, and provide a motion-indicating signal indicating movement relative to the object. An audio processor is coupled to the video processor and is configured and arranged to modify the audio signal to be transmitted responsive to the motion-indicating signal.
An echo-cancellation arrangement is provided in another embodiment. The echo-cancellation arrangement is for a video communication system that includes a microphone, a speaker, and a video camera for use by a video conference participant at a first location and comprises a video signal processor configured and arranged to receive a video signal from the video camera, detect mouth movement of the participant and provide a mouth-movement signal indicative of movement of the participant""s mouth. An echo-cancellation circuit is coupled to the video signal processor and configured and arranged to filter from an audio signal provided by the microphone sound energy output by the speaker responsive to the mouth-movement signal.
A video communication arrangement with video-assisted echo-cancellation is provided in another embodiment. The arrangement is for use by a video conference participant at a first location and comprises a microphone, a speaker, and a video camera arranged to provide a video signal. A video signal processor is coupled to the video camera and is configured and arranged to detect mouth movement of the participant in the video signal and provide a mouth-movement signal indicative of the participant speaking. An echo-cancellation circuit is coupled to the microphone, speaker, and video signal processor and is configured and arranged to filter, responsive to the mouth-movement signal, from an audio signal provided by the microphone sound energy output by the speaker. A video display device is coupled to the processor. A multiplexer is coupled to a channel interface, the echo-cancellation circuit, and the video signal processor, and is configured and arranged to provide audio and video signals as output to the channel interface; and a demultiplexer is coupled to the channel interface, the echo-cancellation circuit, the video display device, and the speaker, and is configured and arranged to provide audio and video signals.
A method is provided for audio signal and video signal processing in accordance with another embodiment. The method comprises receiving a video signal from a video camera. An audio signal from a microphone is received, and movement of an object in the video signal is detected. A motion-indicating signal is provided to an audio signal processor when movement of the object is detected, and the audio signal is modified in response to the motion-indicating signal.
In another embodiment, a method is provided for audio signal and video signal processing. The method comprises receiving a video signal from a video camera. An audio signal is received from a microphone, and movement of a person""s mouth in the video signal is detected. When movement is detected, a motion-indicating signal is provided to an echo-cancellation circuit, and filter coefficients are modified in response to the motion-indicating signal.
An apparatus for audio signal and video signal processing is provided in another embodiment. The apparatus comprises: means for receiving a video signal from a video camera; means for receiving an audio signal from a microphone; means for detecting movement of a person""s mouth in the video signal; means for providing a motion-indicating signal to an echo-cancellation circuit when movement is detected; and means for modifying filter coefficients in response to the motion-indicating signal.
The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description which follow more particularly exemplify these embodiments.